Paclitaxel resistant MDA-MB-231 Cells and resensitization with bexarotene treatment. Homo sapiens

Acquired drug resistance represents a major challenge in chemo-therapy treatment for various types of cancers. We have found that the retinoid X receptor–selective agonist bexarotene (LGD1069, Targretin) was efficacious in treating chemo-resistant cancer cells. The goal of this microarray study was to understand the mechanism of bexarotene’s role in overcoming acquired drug resistance using human breast cancer cells MDA-MB-231 as a model system and paclitaxel as model compound. After MDA-MB-231 cells were repeatedly treated with paclitaxel for 8 cycles with each cycle including a 3-day treatment with 30 nM paclitaxel and followed by a 7-day exposure to control medium, MDA cells resistant to paclitaxel were developed and their growth was no longer inhibited by paclitaxel treatment. Those MDA cells with acquired drug resistance, when treated with paclitaxel and bexarotene in combination, could regain their sensitivity and their growth were again inhibited. Therefore, RNA samples from parental MDA-MB-231 cells, paclitaxel-resistant MDA cells treated with vehicle, paclitaxel alone or in combination with bexarotene, were used for perform global gene expression profiling with Affymetrix HG-U133A gene chips. Keywords: Drug Treatment Overall design: MDA-MB-231 cells were exposed to regimens on a 10-day cycle: a 3-day treatment with 30 nM paclitaxel and followed by a 7-day exposure to control medium. Paclitaxel resistant MDA-MB-231 cells (MDA-PR) were established within 8 cycles of such treatment (80 days). These MDA-PR cells were then treated with vehicle control, paclitaxel along, or the combination of 30 nM paclitaxel ( 3 days on and 7 days off) and 1 µM Targretin (10 days on) in a new 10-day cycle for 3 months. Thus, there are four treatment groups, parent MDA cells, MDA-PR, MDA-PR treated with paclitaxel, MDA-PR treated with paclitaxel and bexarotene, and each group had four biological replicates.

获得性耐药是多种癌症化疗治疗中的重大挑战。本研究发现，视黄醇X受体（retinoid X receptor）选择性激动剂贝沙罗汀（bexarotene，LGD1069，Targretin）对化疗耐药癌细胞具有治疗有效性。本微阵列研究的目的在于，以人乳腺癌细胞MDA-MB-231作为模型系统、以紫杉醇（paclitaxel）作为模型化合物，探究贝沙罗汀逆转获得性耐药的作用机制。

将MDA-MB-231细胞反复进行8轮紫杉醇处理，每轮处理方案为：以30 nM紫杉醇孵育3天，随后更换为正常培养基培养7天。经此流程后，成功获得对紫杉醇产生耐药的MDA细胞，其增殖不再受紫杉醇处理的抑制。此类获得性耐药细胞在联合使用紫杉醇与贝沙罗汀处理后，可恢复对紫杉醇的敏感性，细胞增殖重新受到抑制。

因此，本研究收集了亲本MDA-MB-231细胞、经溶剂对照处理的紫杉醇耐药MDA细胞、单独经紫杉醇处理的紫杉醇耐药MDA细胞，以及联合紫杉醇与贝沙罗汀处理的紫杉醇耐药MDA细胞的RNA样本，采用Affymetrix HG-U133A基因芯片开展全基因组基因表达谱分析。

关键词：药物治疗
实验设计概述：MDA-MB-231细胞采用10天为一个周期的处理方案：以30 nM紫杉醇孵育3天，随后更换为正常培养基培养7天。经8轮（总计80天）此类处理后，成功构建紫杉醇耐药的MDA-MB-231细胞（MDA-PR）。随后将MDA-PR细胞置于新的10天周期方案中处理3个月，处理分组包括：溶剂对照组、单独紫杉醇处理组，以及联合30 nM紫杉醇（3天给药、7天停药）与1 µM贝沙罗汀（全程给药10天）的联合处理组。本研究共设4个处理组：亲本MDA细胞、MDA-PR细胞、紫杉醇处理的MDA-PR细胞、紫杉醇联合贝沙罗汀处理的MDA-PR细胞，每组设置4个生物学重复。